//常见错误
var num1 = 1;
var num2 = 2;
console.log(num1);//1
try{
  //尝试执行
  console.log(num3);//reference error
  //console.log('abc');
}catch(err){
  //console.log(err);
}finally{
  console.log(4);
}

function fn(){
  console.log(123);
}
console.log(num2);//2




